CN101340358B - Flow control method, system and flow control entity - Google Patents
Flow control method, system and flow control entity Download PDFInfo
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Abstract
The invention discloses a method for controlling flow. High threshold and low threshold of cache occupied amount of a target node is pre-arranged. The method comprises that in the process that the flow is transmitted, the cache occupied amount of the target node is monitored, if the cache occupied amount is higher than the high threshold, the transmission flow distributed to the source node is reduced, and the distributed transmission flow is transmitted; if the cache occupied amount is lower than the low threshold, the transmission flow distributed to the source node is increased, and the distributed transmission flow is transmitted. Additionally, the invention also discloses a flow control system and a flow control entity. By the technical proposal disclosed by the invention, the concrete flow control can be realized.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a method, a system, and a flow control entity for controlling flow among nodes.
Background
In wireless communication systems, it is often necessary to transfer data from one node (source node) to another node (target node) before the data is sent by the target node. Since the buffer size of the target node is limited, and the data sending rate of the target node is usually variable and limited, flow control needs to be performed between the source node and the target node to control the data transmission rate from the source node to the target node, so as to prevent the buffer overflow or congestion of the target node.
For example, in a third generation partnership project (3GPP) High Speed Downlink Packet Access (HSDPA) system, the HSDPA has a new MAC-hs entity added to a Medium Access Control (MAC) layer of a base station (Node-B) side, and the HSDPA technology after the MAC-hs entity is added to the Node-B side supports two MAC structures: one is for the Controlling Radio Network Controller (CRNC) to contain a MAC-c/sh entity, and the other is for the CRNC not to contain a MAC-c/sh entity. For the case that the CRNC contains the MAC-c/sh entity, the MAC-hs entity of the Node-B side is connected with the MAC-d entity of the Service Radio Network Controller (SRNC) side through the MAC-c/sh entity of the CRNC side, and then the high-speed downlink data transmission comprises the process from the SRNC to the CRNC and from the CRNC to the Node-B; for the case that the CRNC does not contain the MAC-c/sh entity, the MAC-hs entity of the Node-B side is directly connected with the MAC-d entity of the SRNC side, and the high-speed downlink data transmission comprises the process from the SRNC to the Node-B.
Considering the limited transmission capability of the air interface, in order to reduce the loss and retransmission of data packets caused by layer two (L2) signaling delay and congestion on the high speed downlink shared channel (HS-DSCH), it is necessary to implement data flow control between the CRNC and the Node-B, or between the SRNC and the Node-B. In addition, data flow control can be realized between the SRNC and the CRNC.
Similarly, there is a similar situation between other source nodes and the target node, and it is necessary to implement flow control for data transmission between two nodes, however, there is no specific implementation scheme for flow control in the prior art.
Disclosure of Invention
In view of this, embodiments of the present invention provide a flow control method, and provide a flow control system and a flow control entity to implement a specific flow control.
The flow control method provided by the embodiment of the invention presets a high threshold and a low threshold of the cache occupation of a target node; the method comprises the following steps:
monitoring the cache occupancy of a target node in the flow transmission process, if the cache occupancy is higher than the high threshold, reducing the sending flow allocated to a source node according to the current average output rate of the target node, and sending the allocated sending flow; if the cache occupation amount is lower than the low threshold, the sending flow allocated to the source node is increased according to the current average output rate of the target node, and the allocated sending flow is sent out.
The method further comprises the following steps: and the source node receives the sending flow and sends data to the target node according to the sending flow.
If the cache data volume in the source node is known in advance;
if the cache occupancy of the target node is lower than the low threshold, the method further includes, before increasing the sending traffic allocated to the source node: judging whether the cache data volume in the source node is lower than the sending flow allocated to the source node at the previous time, if not, executing the increase of the sending flow allocated to the source node; otherwise, keeping the current flow unchanged.
The method further comprises the following steps: if the cache overflow of the target node is monitored, sending a notification of temporarily stopping sending data, or distributing sending flow with a value of zero to the source node, and sending the sending flow with the value of zero;
and the source node stops sending data to the target node after receiving the notification of temporarily stopping sending data or the sending flow with the value of zero.
Preferably, after the source node stops sending data to the target node, the method further comprises: the source node starts a preset timer and sends out a flow request when the time of the timer is up;
and executing the monitoring of the cache occupancy of the target node according to the received flow request.
Or, sending a notification of temporarily stopping sending data, or sending a sending flow with a value of zero, and then further comprising: and starting a preset timer, and executing monitoring of the cache occupation amount of the target node when the time of the timer is up.
Wherein, the adjusting down of the sending flow allocated to the source node according to the current average output rate of the target node is as follows: obtaining a source node sending rate value lower than the current average output rate of a target node according to the current average output rate of the target node and a preset rate reduction factor, and determining the sending flow of a source node according to the source node sending rate value;
the method for increasing the sending flow allocated to the source node according to the current average output rate of the target node comprises the following steps: according to the current average output rate of the target node and a preset rate increasing factor, obtaining a source node sending rate value higher than the current average output rate of the target node, and determining the sending flow of the source node according to the source node sending rate value.
The current average output rate of the target node is: formula (II)
Or
Wherein,
is the current average output rate of the target node,
is the previous average output rate, R, of the target nodest(T) is the current output rate of the target node, η is the low-pass filter factor, and T is the communication duration.
The sending rate value of the source node, which is lower than the current average output rate of the target node, obtained according to the current average output rate of the target node and a preset rate reduction factor is as follows: formula (II)
Wherein R isrt(t) is the sending rate value of the source node,
is the current average output rate of the target node, and β is the rate reduction factor.
The sending rate value of the source node, which is obtained according to the current average output rate of the target node and the preset rate increasing factor and is higher than the current average output rate of the target node, is: formula (II)
Wherein R isrt(t) is the sending rate value of the source node,alpha is the rate boost factor, which is the current average output rate of the target node.
If the target Node is a base station Node-B, the source Node is a radio network controller RNC;
then, the determining the sending flow of the source node according to the sending rate value of the source node is as follows: according to Rrt(t) using the formulaObtaining the number of data packets transmitted by a source node at one time, and taking the number of the data packets transmitted by the source node at one time as sending flow control information of the source node; wherein, Credit is the number of data packets transmitted by the source node at one time, RrtAnd (t) is a sending rate value of the source node, Interval is a time Interval of two data transmissions of the source node, and SIZE is a data packet SIZE transmitted by the source node.
The flow control system provided by the embodiment of the invention comprises: a source node, a target node and a flow control entity, wherein,
the flow control entity is used for monitoring the cache occupancy of the target node in the flow transmission process, if the cache occupancy is higher than a preset high threshold, the sending flow distributed to the source node is adjusted to be low according to the current average output rate of the target node, and the distributed sending flow is sent to the source node; if the cache occupancy is lower than a preset low threshold, increasing the sending flow allocated to the source node according to the current average output rate of the target node, and sending the allocated sending flow to the source node;
the source node is configured to receive the sending traffic from the traffic control entity, and send data to the target node according to the sending traffic.
Preferably, the flow control entity further obtains the amount of cache data in the source node, and further determines whether the amount of cache data in the source node is lower than the sending flow allocated to the source node at the previous time before the flow control entity monitors that the cache occupancy amount of the target node is lower than the low threshold and increases the sending flow allocated to the source node, and if not, performs the increase of the sending flow allocated to the source node; otherwise, keeping the current flow unchanged.
Wherein the flow control entity is disposed in the target node.
The embodiment of the invention provides a flow control entity, which comprises:
the target node cache occupancy monitoring module is used for monitoring the cache occupancy of the target node in the flow transmission process and providing the cache occupancy to the flow control module;
the target node average output rate calculation module is used for calculating the current average output rate of the target node and providing the current average output rate of the target node to the flow control module;
the flow control module is used for reducing the sending flow distributed to the source node according to the current average output rate of the target node when the cache occupancy is higher than a preset high threshold, and sending the distributed sending flow; and when the cache occupancy is lower than a preset low threshold, increasing the sending flow allocated to the source node according to the current average output rate of the target node, and sending the allocated sending flow.
Preferably, the flow control entity further comprises: a source node cache data volume acquiring module, configured to acquire a source node cache data volume and provide the source node cache data volume to the flow control module;
when the cache occupancy is lower than a preset low threshold, the flow control module increases the sending flow allocated to the source node, and further judges whether the cache data volume in the source node is lower than the sending flow allocated to the source node at the previous time, if not, the flow control module increases the sending flow allocated to the source node; otherwise, keeping the current flow unchanged.
According to the scheme, the high threshold and the low threshold of the cache occupation of the target node are preset in the embodiment of the invention; monitoring the cache occupancy of a target node in the flow transmission process, if the cache occupancy is higher than a high threshold, reducing the sending flow distributed to a source node, and sending out the distributed sending flow; if the cache occupancy is lower than the low threshold, the sending flow allocated to the source node is increased, and the allocated sending flow is sent out, so that the flow control is realized.
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Fig. 1 is an exemplary flowchart of a flow control method in an embodiment of the present invention.
Fig. 2 is an exemplary configuration diagram of a flow control system in an embodiment of the present invention.
Fig. 3 is an exemplary structural diagram of a flow control entity in an embodiment of the present invention.
Fig. 4 is a block diagram of a flow control system in an embodiment of the present invention.
Fig. 5 is a flowchart of a flow control method in an embodiment of the present invention.
Detailed Description
In the embodiment of the invention, a high threshold and a low threshold of the cache occupancy of a target node are preset, and the high threshold is larger than the low threshold; monitoring the cache occupancy of a target node in the flow transmission process, if the cache occupancy is higher than a high threshold, reducing the sending flow distributed to a source node, and sending out the distributed sending flow; and if the cache occupation amount is lower than the low threshold, increasing the sending flow allocated to the source node, and sending the allocated sending flow out.
In a specific implementation, the sending traffic allocated to the source node may be represented by the sending rate, the sending number, the size of the sent data packet, or the like, as long as the function of adjusting the traffic is achieved.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments and the accompanying drawings.
Fig. 1 is an exemplary flowchart of a flow control method in an embodiment of the present invention. As shown in fig. 1, the process includes the following steps:
step 101, presetting a high threshold of cache occupancy of a target node
Sum low threshold
And is
Is greater than
Because different systems have different characteristics, such as different buffer capacity sizes, different data transmission characteristics, and the like, the system has the advantages of being simple in structure, convenient to use, and capable of reducing the cost of the systemAnd
the value of (b) can be determined according to the situation of the specific application. Wherein,
the cache capacity is smaller than the maximum cache capacity of the target node and is used for preventing the cache of the target node from overflowing;
the method and the device are used for preventing the existing data of the target node from being sent completely before the source node sends the next data to the target node, so that the data sending delay is caused.
And 102, monitoring the cache occupancy of the target node.
In this embodiment, since the flow control only relates to the flow transmission process, the initial sending state of the source node, such as the sending rate, the size and the number of the data packets, is not limited in this embodiment. The source node may send a certain amount of data to the destination node in an initial state, such as 50% of the data amount sent to the destination node for the destination node to pre-store in the cache for data transmission.
And then monitoring the cache occupancy of the target node in the flow transmission process.
Step 103, judging the cache occupation amount and the high threshold of the target node
Sum low threshold
If the cache occupancy of the target node is higher than that of the target node
Step 104 is executed; if the cache occupancy of the target node is lower than
Step 105 is executed; if the cache occupancy of the target node is betweenAnd
then step 106 is performed.
Step 104, the sending flow rate distributed to the source node is reduced, the distributed sending flow rate is sent out, and the step 102 is executed again.
And after receiving the sending flow, the source node sends data to the target node according to the sending flow.
In this step, there may be various ways to reduce the sending traffic allocated to the source node, for example, low traffic adjustment may be performed directly on the basis of the sending traffic of the source node, and the sending traffic allocated to the source node at this time is obtained by subtracting a value greater than zero from the traffic allocated to the source node at the previous time, or dividing by a value greater than 1, or multiplying by a value less than 1, and the like.
For another example, the current average sending traffic of the target node may be calculated in real time, and then low traffic adjustment is performed on the basis of the calculated current average sending traffic of the target node, and the sending traffic allocated to the source node at this time is obtained by subtracting a value greater than zero from the current average sending traffic of the target node, or dividing the value greater than 1 by the value greater than 1, or multiplying the value less than 1 by the value.
Taking the case of adjusting the sending rate as an example, the current average output rate of the target node can be calculated according to the following formula (1): <math><mrow> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mi>η</mi> <mo>)</mo> </mrow> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>+</mo> <mi>η</mi> <msub> <mi>R</mi> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow></math>
wherein R isst(t) is the current average output rate of the target node, Rst(t-1) is the previous average output rate of the target node, Rst(t) is the current output rate of the target node, and η is the low-pass filter factor. The greater the eta value is, the greater the current value occupation ratio is, otherwise, the smaller the current value occupation ratio is, the specific size of eta can be determined according to the fluctuation of the data flow of the network, if the fluctuation is greater, the smaller the value is, otherwise, the greater the value is.
Or the current average output rate of the target node can also be calculated according to the following formula (2):
wherein T is a communication duration.
The value of the transmission rate allocated to the source node can be calculated according to the following formula (3):
wherein R isrt(t) is the sending rate value of the source node, Rst(t) is the current average output rate of the target node, and β is the rate reduction factor. Wherein the value of beta is more than 1, and if the threshold is highIf the beta value is set to be very high, the beta value can be slightly larger, and conversely, the beta value can be slightly smaller. In addition, the beta value can also be preset with a plurality of values and dynamically selected according to the condition of the cache occupancy of the target node.
And 105, increasing the sending flow distributed to the source node, sending the distributed sending flow out, and returning to execute the step 102.
And after receiving the sending flow, the source node sends data to the target node according to the sending flow.
In this step, there may be various ways to increase the sending traffic allocated to the source node, for example, high traffic adjustment may be directly performed on the basis of the sending traffic of the source node, and the sending traffic allocated to the source node at this time is obtained by adding a value greater than zero to the traffic allocated to the source node at the previous time, or dividing the value by a value smaller than 1, or multiplying the value by a value greater than 1.
For another example, if the current average sending traffic of the target node is calculated in real time, high traffic adjustment may be performed on the basis of the calculated current average sending traffic of the target node, and the current average sending traffic of the target node is added with a value greater than zero or divided by a value less than 1 or multiplied by a value greater than 1, so as to obtain the sending traffic allocated to the source node this time.
Taking the case of adjusting the sending rate as an example, the current average output rate of the target node can also be according to the formula described in step 104 <math><mrow> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mi>η</mi> <mo>)</mo> </mrow> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>+</mo> <mi>η</mi> <msub> <mi>R</mi> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow></math> Or <math><mrow> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <munder> <mi>Σ</mi> <mi>t</mi> </munder> <msub> <mi>R</mi> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>/</mo> <mi>T</mi> </mrow></math> And (6) performing calculation.
The value of the transmission rate allocated to the source node may be calculated according to the following equation (4):
wherein R isrt(t) is the sending rate value of the source node, Rst(t) is the current average output rate of the target node, and α is the rate boost factor. Wherein, the alpha value can be made as small as possible, but it needs to ensure that the data transmission in the target node is not completed, if the threshold is lowIf the value is set to be very low, the value of alpha can be slightly larger, and conversely, the value of alpha can be slightly smaller. In addition, a plurality of values can be preset for the alpha value, and the alpha value can be dynamically selected according to the cache occupancy of the target node.
In this step, if the amount of the cache data in the source node can be known in advance, it is further determined whether the amount of the cache data in the source node is lower than the sending flow allocated to the source node at the previous time before the sending flow allocated to the source node is increased, and if not, the sending flow allocated to the source node is increased; otherwise, execution may return to step 102. If the residual cache data volume in the source node can be sent out at one time by using the previous sending flow, the sending flow does not need to be increased at this time, so that unnecessary resource consumption and additional signaling interaction are avoided.
And step 106, keeping the current flow unchanged, and returning to execute the step 102.
In this step, to avoid extra signaling overhead, when the cache occupancy of the target node is in the middleAnd
in between, the transmission traffic of the source node is not controlled, and thus new transmission traffic allocation information is not transmitted to the source node. The source node still transmits data according to the original flow. In a specific implementation, the traffic of the source node may also be controlled, for example, the current average output traffic of the target node is calculated in advance, and the current average output traffic of the target node is used as the sending traffic of the source node.
When the flow of the method is specifically performed, the flow control entity arranged in the target node or arranged outside the target node performs the flow control, and if the flow control entity is arranged outside the target node, information interaction with the target node is required to be performed so as to obtain information such as cache occupancy of the target node.
After the flow control is performed, the target node cache overflow will not occur in a normal situation, but for the sake of insurance, the embodiment may further include: in step 103, if it is monitored that the cache of the target node overflows, a notification of temporarily stopping sending data is sent out, or a sending flow with a value of zero is allocated to the source node, and the sending flow with a value of zero is sent out.
And the source node stops sending data to the target node when receiving the notification of temporarily stopping sending data or the sending flow with the value of zero.
Thereafter, the method can return to the step 102 to continue monitoring the cache occupancy of the target node. Or further, in order to allow the target node sufficient time to process the buffered data, the flow control entity may further start a preset timer after sending a notification to temporarily stop sending the data, or sending a sending flow with a value of zero, and when the time length of the timer is reached, return to step 102. Or after the source node stops sending data to the target node, the source node further starts a preset timer, and sends out the flow request when the time of the timer is reached; the flow control entity returns to perform step 102 according to the received flow request.
Still alternatively, in each of the above cases, before returning to the step 102, the following steps may be further included:
step 201, monitoring the cache occupancy of the target node.
Step 202, determining the cache occupancy and high threshold of the target node
Sum low threshold
If the cache occupancy of the target node is higher than that of the target node
Returning to execute the step 201; if the cache occupancy of the target node is lower than
Step 105 is executed; if the cache occupancy of the target node is between
Andin between, the pre-calculated current average output traffic of the target node may be sent to the source node as the sending traffic of the source node, and then the step 102 is executed again.
The flow control method in the embodiment of the present invention is described in detail above, and the flow control system in the embodiment of the present invention is described in detail below.
Fig. 2 shows an exemplary configuration diagram of a flow control system in an embodiment of the present invention. As shown in fig. 2, the system includes: a source node, a target node and a flow control entity.
The flow control entity is used for monitoring the cache occupancy of a target node in the flow transmission process, if the cache occupancy is higher than a preset high threshold, reducing the sending flow distributed to a source node, and sending the distributed sending flow to the source node; and if the cache occupancy is lower than a preset low threshold, increasing the sending flow allocated to the source node, and sending the allocated sending flow to the source node.
The source node is used for receiving the sending flow from the flow control entity and sending data to the target node according to the received sending flow.
Further, the flow control entity learns the cache data volume in the source node, and when monitoring that the cache occupancy of the target node is lower than the low threshold, the flow control entity further determines whether the cache data volume in the source node is lower than the sending flow allocated to the source node at the previous time before increasing the sending flow allocated to the source node, and if not, increases the sending flow allocated to the source node.
Here, the procedure of turning down the transmission traffic allocated to the source node may be consistent with the description in step 104 shown in fig. 1, and the procedure of turning up the transmission traffic allocated to the source node may be consistent with the description in step 105 shown in fig. 1. For example, the flow control entity further calculates the current average output rate of the target node, and performs an operation of allocating the transmission flow to the source node according to the calculated current average output rate of the target node. The specific process may be consistent with the description of the method flow shown in fig. 1.
The flow control entity may be located in the target node or outside the target node. If the flow control entity is arranged outside the target node, information interaction with the target node is required to be carried out so as to obtain information such as cache occupancy of the target node.
In addition, when the flow control entity is implemented, the flow control entity can have various implementation forms. The detailed implementation of the flow control entity is described in detail below only by way of an example of one of the structural forms.
Fig. 3 is an exemplary structural diagram of a flow control entity in an embodiment of the present invention. As shown in the solid line part of fig. 3, the flow control entity includes: the device comprises a target node cache occupancy monitoring module and a flow control module.
The target node cache occupancy monitoring module is used for monitoring the cache occupancy of the target node in the flow transmission process and providing the monitored cache occupancy to the flow control module.
The flow control module is used for reducing the sending flow distributed to the source node when the cache occupation of the target node is higher than a preset high threshold, and sending the distributed sending flow out; and when the cache occupation amount of the target node is lower than a preset low threshold, increasing the sending flow allocated to the source node, and sending out the allocated sending flow.
Further, as shown in the dotted line part in fig. 3, the flow control entity further includes: and the source node cache data volume acquisition module is used for acquiring the cache data volume of the source node and providing the cache data volume of the source node to the flow control module. And when the cache occupation amount is lower than a preset lower threshold, the flow control module further judges whether the cache data amount in the source node is lower than the sending flow allocated to the source node at the last time before increasing the sending flow allocated to the source node, and if not, the flow control module executes the operation of increasing the sending flow allocated to the source node.
The process of turning down the sending traffic allocated to the source node by the traffic control entity may be consistent with the description in step 104 shown in fig. 1, and the process of turning up the sending traffic allocated to the source node may be consistent with the description in step 105 shown in fig. 1. For example, the flow control entity may further include: and the target node average output rate calculation module is used for calculating the current average output rate of the target node and providing the calculated current average output rate of the target node to the flow control module. And the flow control module executes the operation of distributing the sending flow to the source node according to the current average output rate of the target node. The specific process may be consistent with the description of the method flow shown in fig. 1.
The method, system and flow control entity described above will be described in detail by a specific application embodiment.
In this embodiment, taking the flow control on the HS-DSCH of the Iub interface (i.e. the interface between the RNC and the Node-B) in the HSDPA system as an example, in the HSDPA system, the functions of the MAC layer on the network side are separated and controlled by the RNC and the Node-B, respectively. The function of the MAC-d layer is mainly in the RNC entity, and the function of the MAC-hs entity is mainly realized in the Node-B entity, wherein the other important function of the MAC-hs entity except the realization of the dispatching and HARQ related functions is the flow control function, therefore, the flow control entity in the embodiment of the application is the MAC-hs entity, the source Node is the RNC entity, the target Node is the Node-B entity, and the flow control entity is arranged in the target Node.
In HSDPA, RNC generates MAC-d data Packet (PDU) and transmits it to Node-B entity through interface-Iub interface between RNC and Node-B, Node-B caches (destination Node caches) each data packet with different priority, then according to certain scheduling criterion, these data are transmitted on air interface. Taking the case that the CRNC does not include the MAC-c/sh entity as an example, the MAC layer function layering and flow control entity in the HSDPA is shown in fig. 4. Fig. 4 includes RNC and Node-B, and the MAC-hs entity of the flow control entity located in Node-B.
The MAC-hs entity is used for monitoring the cache occupation amount of the Node-B in the flow transmission process, if the cache occupation amount is higher than a preset high threshold, the sending flow allocated to the RNC is reduced, and the allocated sending flow is sent to the RNC; and if the cache occupation amount is lower than a preset low threshold, increasing the sending flow allocated to the RNC, and sending the allocated sending flow to the RNC.
The RNC is used for receiving the sending flow from the MAC-hs entity and sending data to the Node-B according to the received sending flow. Wherein, MAC-d entity in RNC controls to send data to Node-B according to received sending flow.
As mentioned above, the flow control may be embodied as controlling a data transmission rate from the source node to the destination node, preventing a cache overflow of the destination node, controlling a cache delay of data in the destination node, and preventing a congestion. In HSDPA, this function is mainly achieved by dynamically adjusting the values of several parameters: the Size of the transmitted MAC-d data packet (Max MAC-d PDU Size) is recorded as Size; the number (Credit) of MAC-d data packets transmitted at one time on the Iub interface is marked as Credit; the time Interval (Interval) between two data transmissions on the Iub interface is denoted as Interval; and the number of valid times (Repetition Period) for which the above setting continues.
From the configuration of these several parameters, the maximum allowed data transmission rate on the Iub interface, and the data entry rate of the MAC-hs buffer can be calculated according to the following equation (5):
it can be seen that the data transmission rate on the Iub interface is mainly determined by the first three parameters, and the last parameter represents the effective time of the data transmission rate, so that the Node-B can dynamically adjust the rate. It can be seen that the flow control algorithm on the Iub interface has the most important functions: the setting and adjustment of the speed are realized to control the data transmission speed on the interface, and the buffer storage and the data packet time delay of the Node-B side are effectively controlled.
The flow control mainly relates to two types of control frames and a data frame, the control frame is mainly used for signaling interaction and realizing a control function, the data frame is mainly used for data transmission, and the data frame also carries corresponding state information for control. The control frame is: CAPACITY request (CAPACITY request) frame and CAPACITY ALLOCATION (CAPACITY ALLOCATION) frame, the data frame is: high speed-downlink shared channel DATA (HS-DSCH DATA) frames.
Wherein, CAPACITY REQUEST is used for the source Node RNC to REQUEST the CAPACITY resource from the destination Node-B for data transmission, when the data reaches the RNC but there is no available Iub CAPACITY resource, the RNC uses the frame to REQUEST the resource from the MAC-hs entity of the corresponding Node-B. The Node-B responds to the request with a CAPACITY ALLOCATION, which includes therein the corresponding ALLOCATION of CAPACITY to the corresponding priority data. In addition, the Node-B can also use the frame to dynamically and actively adjust the data transmission rate.
The HS-DSCH DATA FRAME is used for transmitting data on the HS-DSCH and includes corresponding control information in addition to the data, such as occupancy of a buffer radio link layer (RLC) buffer of the RNC.
Presetting high threshold of cache occupancy of target nodeSum low threshold
And is
Is greater than
In addition, the formula (1) is used to smooth the data output rate of the MAC-hs buffer, namely the data output rate of the Node-B, and the current average of the Node-B is obtainedThe output rate. The specific flow rate distribution and adjustment process is shown in fig. 5, and fig. 5 is a flowchart of a flow rate control method in an embodiment of the present invention. The process comprises the following steps:
In this step, first, according to the formula (4), that is <math><mrow> <msub> <mi>R</mi> <mi>rt</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>+</mo> <mi>α</mi> </mrow></math> Calculating to obtain a sending rate value R allocated for the RNCrt(t), R in the formula (5)Iub。
In addition, in HSDPA, the newly allocated R may be set in consideration of protocol realizabilityrt(t) translates to setting of corresponding parameters in the protocol. For example, converting to a parameter Credit, Credit can be calculated according to equation (6):
setting the Interval to a fixed value according to the bearing capacity of the Iub interface transmission network, and not needing to change within a certain time; the size of the MAC-d PDU can also be a fixed value, the size can be well negotiated when the bearing is established, and the size is basically unchanged in the data transmission process. If the two parameters are changed, the number credit of the MAC-d PDUs transmitted in an Interval can still be calculated according to the formula; repetition Period is set to 2047 (indicating that the allocation is valid until the next time a new capacity allocation is received).
After the four parameters (MAC-d PDU Size, Credit, Interval, Repetition Period) are obtained, the field in the corresponding protocol frame is set, and then the new transmission traffic ALLOCATION is sent to the RNC through the CAPACITY ALLOCATION frame.
And after receiving the distributed parameters through the MAC-d entity, the RNC sends data to the Node-B according to the parameter information.
In this step, to avoid extra signaling overhead, when the cache occupancy of Node-B is between
And
in the meantime, the transmission flow of the RNC is not controlled, so that new transmission flow allocation information is not transmitted to the RNC, and the RNC still transmits data according to the original flow. In the specific implementation, the flow of the RNC may also be controlled, for example, the current average output rate of the Node-B is calculated in advance, the current average output rate of the Node-B is used as the sending rate of the RNC, and further, according to the method described in step 503, the current average output rate of the Node-B is converted into the setting of the corresponding parameter in the protocol and sent to the RNC.
In this step, first according to formula (3), i.e. <math><mrow> <msub> <mi>R</mi> <mi>rt</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>+</mo> <mi>β</mi> </mrow></math> Calculating to obtain a sending rate value R allocated for the RNCrt(t), R in the formula (5)Iub. The newly assigned R may then be compared to the value of R as described in step 503rt(t) the settings converted into corresponding parameters in the protocol are sent to the RNC.
In step 507, a notification to temporarily stop data transmission is transmitted to the RNC.
After receiving the notice of temporarily stopping sending data, RNC stops sending data to Node-B, starts up the preset timer, and sends CAPACITYREQUEST frame to Node-B when the time of the timer is reached.
In step 508, the Node-B determines whether a CAPACITY REQUEST frame is received from the RNC and if so, proceeds to step 509.
In this step, the <math><mrow> <msub> <mi>R</mi> <mi>rt</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mover> <mi>R</mi> <mo>‾</mo> </mover> <mi>st</mi> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow></math> As value of transmission rate R allocated for RNCrt(t), R in the formula (5)IubThe newly assigned R may then be compared to the method described in step 503rt(t) the settings converted into corresponding parameters in the protocol are sent to the RNC.
In summary, the flow control scheme in the preferred embodiment of the present invention has the following advantages:
1. the method has strong universality and is suitable for a plurality of scenes and systems. As long as data transmission between two nodes is involved, the technical scheme in the embodiment of the invention can be used in the scene that the cache size of the target node is limited and the data sending rate is limited. Generally, such scenarios are typical scenarios requiring flow control, that is, the scheme can be applied to any scenario requiring flow control, such as WCDMA
R99/R4, TD-SCDMA R99/R4, etc.
2. And strictly controlling the occupation of the cache of the target node. The technical scheme of the embodiment of the invention sets a high threshold of the cache occupancy, once the cache occupancy is greater than the high threshold, the flow of data sent by the source node to the target node is immediately reduced, and the reduction of the rate can adopt an exponential descent method, so that the cache occupancy is quickly controlled. On one hand, the overflow of the limited size cache of the target node is prevented, on the other hand, the cache of the target node needs to be cleared in certain scenes, and data is discarded (for example, in HSDPA, when switching occurs, when SRNC is used for transmitting Forward Access Channel (FACH) and Downlink Shared Channel (DSCH), channel switching occurs, cell reselection occurs and the like), at the moment, the occupation of the cache of the target node is controlled, so that a large amount of data can be avoided being discarded as much as possible, the retransmission (if existing) probability of an upper layer is reduced, and the data transmission delay is reduced.
3. Minimum queuing delay. Because the high threshold of the cache occupation is set, and when the data sending rate of the source node is matched with the data sending rate of the target node cache, the technical scheme in the embodiment of the invention can obtain small data packet queuing delay.
4. And keeping the occupation of a certain data volume in the cache of the target node. The technical scheme of the embodiment of the invention sets a low threshold of the cache occupancy of the target node, and when the data occupancy in the cache is lower than the low threshold, the data sending rate of the source node to the target node is increased, so that the situation that the data sending rate of the target node is reduced due to too small data amount in the cache of the target node when the data transmission rate between the source node and the target node is too low and the data is needed to be sent by the target node is avoided.
5. The signaling load is small. The technical scheme in the embodiment of the invention adopts a series of methods to reduce the signaling load. Firstly, if the cache occupation amount of the target node is between the high threshold and the low threshold, the data sending rate of the source node is not changed, and the flow adjustment indication is not sent to the source node. Secondly, if the cache occupancy of the target node is lower than the low threshold, but the data volume cached by the source node is smaller than the sending flow allocated at the previous time, new flow allocation is not sent to the source node.
6. The implementation is simple, the technical scheme in the embodiment of the invention only needs to continuously monitor the cache occupancy of the target node, further counts the average output rate of the data of the cache, then controls the flow of the source node according to the process described in the embodiment of the invention, and the realization of hardware and software is simple.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above-mentioned embodiments are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (16)
1. A flow control method is characterized in that a high threshold and a low threshold of the cache occupancy of a target node are preset; the method comprises the following steps:
monitoring the cache occupancy of a target node in the flow transmission process, if the cache occupancy is higher than the high threshold, reducing the sending flow allocated to a source node according to the current average output rate of the target node, and sending the allocated sending flow; if the cache occupation amount is lower than the low threshold, the sending flow allocated to the source node is increased according to the current average output rate of the target node, and the allocated sending flow is sent out.
2. The method of claim 1, further comprising: and the source node receives the sending flow and sends data to the target node according to the sending flow.
3. The method of claim 1, wherein the amount of cache data in the source node is known in advance;
if the cache occupancy of the target node is lower than the low threshold, the method further includes, before increasing the sending traffic allocated to the source node: judging whether the cache data volume in the source node is lower than the sending flow allocated to the source node at the previous time, if not, executing the increase of the sending flow allocated to the source node; otherwise, keeping the current flow unchanged.
4. The method of claim 1, further comprising: if the cache overflow of the target node is monitored, sending a notification of temporarily stopping sending data, or distributing sending flow with a value of zero to the source node, and sending the sending flow with the value of zero;
and the source node stops sending data to the target node after receiving the notification of temporarily stopping sending data or the sending flow with the value of zero.
5. The method of claim 4, wherein after the source node stops sending data to the target node, further comprising: the source node starts a preset timer and sends out a flow request when the time of the timer is up;
and executing the monitoring of the cache occupancy of the target node according to the received flow request.
6. The method of claim 4, wherein sending a notification to temporarily stop sending data, or sending a sending traffic with a value of zero, further comprises: and starting a preset timer, and executing monitoring of the cache occupation amount of the target node when the time of the timer is up.
7. The method of any of claims 1 to 6, wherein the throttling down the transmission traffic allocated to the source node based on the current average output rate of the target node is: obtaining a source node sending rate value lower than the current average output rate of a target node according to the current average output rate of the target node and a preset rate reduction factor, and determining the sending flow of a source node according to the source node sending rate value;
the method for increasing the sending flow allocated to the source node according to the current average output rate of the target node comprises the following steps: according to the current average output rate of the target node and a preset rate increasing factor, obtaining a source node sending rate value higher than the current average output rate of the target node, and determining the sending flow of the source node according to the source node sending rate value.
8. The method of claim 7, wherein the current average output rate of the target node is: formula (II)
Or
Wherein,
is the current average output rate of the target node,
is the previous average output rate, R, of the target nodest(T) is the current output rate of the target node, η is the low-pass filter factor, and T is the communication duration.
9. The method as claimed in claim 7, wherein the obtaining of the sending rate value of the source node lower than the current average output rate of the target node according to the current average output rate of the target node and a preset rate reduction factor is: formula (II)Wherein R isrt(t) is the sending rate value of the source node,
is the current average output rate of the target node, and β is the rate reduction factor.
10. The method as claimed in claim 7, wherein the obtaining of the sending rate value of the source node higher than the current average output rate of the target node according to the current average output rate of the target node and a preset rate boost factor is: formula (II)
Wherein R isrt(t) is the sending rate value of the source node,
alpha is the rate boost factor, which is the current average output rate of the target node.
11. The method of claim 7, wherein the target Node is a base station Node-B, and the source Node is a radio network controller RNC;
determining the sending flow of the source node according to the sending rate value of the source node as follows: according to Rrt(t) using the formulaObtaining the number of data packets transmitted by a source node at one time, and taking the number of the data packets transmitted by the source node at one time as sending flow control information of the source node; wherein, Credit is the number of data packets transmitted by the source node at one time, RrtAnd (t) is a sending rate value of the source node, Interval is a time Interval of two data transmissions of the source node, and SIZE is a data packet SIZE transmitted by the source node.
12. A flow control system, comprising: a source node, a target node and a flow control entity, wherein,
the flow control entity is used for monitoring the cache occupancy of the target node in the flow transmission process, if the cache occupancy is higher than a preset high threshold, the sending flow distributed to the source node is adjusted to be low according to the current average output rate of the target node, and the distributed sending flow is sent to the source node; if the cache occupancy is lower than a preset low threshold, increasing the sending flow allocated to the source node according to the current average output rate of the target node, and sending the allocated sending flow to the source node;
the source node is configured to receive the sending traffic from the traffic control entity, and send data to the target node according to the sending traffic.
13. The system of claim 12, wherein the flow control entity further learns the amount of cache data in the source node, and further determines whether the amount of cache data in the source node is lower than the previous transmission flow allocated to the source node before increasing the transmission flow allocated to the source node when monitoring that the cache occupancy of the target node is lower than the low threshold, and if not, performs the increase of the transmission flow allocated to the source node, otherwise, keeps the current flow unchanged.
14. The system of claim 13 wherein said flow control entity is disposed in said target node.
15. A flow control entity, comprising:
the target node cache occupancy monitoring module is used for monitoring the cache occupancy of the target node in the flow transmission process and providing the cache occupancy to the flow control module;
the target node average output rate calculation module is used for calculating the current average output rate of the target node and providing the current average output rate of the target node to the flow control module;
the flow control module is used for reducing the sending flow distributed to the source node according to the current average output rate of the target node when the cache occupancy is higher than a preset high threshold, and sending the distributed sending flow; and when the cache occupancy is lower than a preset low threshold, increasing the sending flow allocated to the source node according to the current average output rate of the target node, and sending the allocated sending flow.
16. The traffic control entity of claim 15, wherein the traffic control entity further comprises: a source node cache data volume acquiring module, configured to acquire a source node cache data volume and provide the source node cache data volume to the flow control module;
when the cache occupancy is lower than a preset low threshold, the flow control module increases the sending flow allocated to the source node, and further judges whether the cache data volume in the source node is lower than the sending flow allocated to the source node at the previous time, if not, the flow control module increases the sending flow allocated to the source node; otherwise, keeping the current flow unchanged.
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| CN102487531B (en) * | 2010-12-06 | 2014-07-02 | 普天信息技术研究院有限公司 | Flow control method for flow self-adaption modification of Iub port |
| CN103067937B (en) * | 2012-12-04 | 2016-04-20 | 大唐移动通信设备有限公司 | state information processing method and system |
| CN103067474A (en) * | 2012-12-21 | 2013-04-24 | 曙光信息产业(北京)有限公司 | Processing method and device for communication in distributed file system |
| CN104869073B (en) * | 2014-02-26 | 2019-09-06 | 中兴通讯股份有限公司 | A kind of flow control methods and device |
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| CN106100992A (en) * | 2016-06-14 | 2016-11-09 | 北京信息科技大学 | Data transmitting equipment and method thereof |
| CN112559390B (en) * | 2016-09-23 | 2023-06-06 | 成都华为技术有限公司 | Data writing control method and storage device |
| TWI777938B (en) * | 2017-01-24 | 2022-09-21 | 香港商阿里巴巴集團服務有限公司 | Information flow control method, device and related system |
| CN109379163B (en) * | 2018-09-05 | 2021-11-23 | 新华三技术有限公司 | Message forwarding rate control method and device |
| CN110351595B (en) | 2019-07-17 | 2023-08-18 | 北京百度网讯科技有限公司 | Buffer processing method, device, equipment and computer storage medium |
| CN113055300B (en) * | 2019-12-27 | 2024-09-10 | 阿里巴巴集团控股有限公司 | Flow control method and device |
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